« AnteriorContinuar »
called putrefaction : but these distinctions carbonic acid gas. The carbon and hydroare
not essential; for putrefying animal gen are derived, ultimately, from the food. matters will cause sugar to ferment, as well By comparing the amount of oxygen
abas common yest. The fetid smell of putre- sorbed with that of carbonic acid given out, faction is chiefly owing to ammonia; and and with that of the food consumed, the hence it is observed not only in the fermen- author demonstrates thattation of animal matter, but also of such « The amount of nourishment required for its vegetable bodies as contain nitrogen, and support by the animal body must be in a direct therefore yield ammonia.
ratio to the quantity of oxygen taken into the Now the explanation given by our author system.' of these and similar changes is this : that But the amount of oxygen inspired varies the ferment, or exciting body, is invariably very much. It is increased by motion or a substance in an active state of decompo- exercise, which increases the number of sition. Its particles are therefore in a state respirations : it is increased by cold, which of motion ; and this motion, being commu- renders the air more dense; and it is also nicated to those of the body to be meta- increased in proportion as the barometer morphosed, is sufficient to overturn their rises, for the same reason. very unstable equilibrium, and to cause the formation of new and more stable com- "The consumption of oxygen in equal times pounds. The more complex the original may be expressed by the number of respirations :
it is clear that, in the same individual, the quancompound, the more easily does it undergo metamorphosis. The Professor has pro- force and number of the respirations. A child,
tity of nourishment required must vary with the duced, in support of this doctrine, an extra- in whom the organs of respiration are naturally ordinary number of facts, and has, by strict in a state of greater activity, requires food oftener, induction from these, demonstrated it al- and in greater proportion to its bulk, than an most mathematically. It appears to us that adult, and bears hunger less easily. A bird, dehe has for ever banished the notion of the prived of food, dies on the third day; while a catalytic force-an unknown and mysteri- serpent, which, if kept under a bell-jar, hardly ous power which some writers had invoked consumes in an hour so much oxygen as that
we can detect the carbonic acid produced, can to explain the phenomena of chemical live without food three months and longer. transformations.
In summer and winter, at the pole and at the When we turn our attention to the living equator, we respire an equal volume of air. In animal body, there are certain processes or summer, the air contains aqueous vapour, while operations which at once present them- in winter it is dry: The space occupied by vaselves as the most interesting. Among pour in warm air is filled up by air itself in win
ter: that is, an equal volume of air contains these may be mentioned respiration, nutri
more oxygen in winter than in summer. tion, the waste and supply of matter, diges- "The cold air is warmed in the air-passages tion, secretion, and excretion, with the and in the cells of the lungs, and acquires the bearings of all on health and disease. On temperature of the body. To introduce the all of these subjects the views of the author same volume of oxygen into the lungs, a smaller are equally original and interesting.
expenditure of force is necessary in winter than
in summer; and for the same expenditure of • Wonders,' he remarks, surround us on every force, more oxygen is inspired in winter than in side. The formation of a crystal, of an octahe- summer. dron, is not less incomprehensible than the pro- "The oxygen taken into the system is given duction of a leaf or of a muscular fibre; and the out again in the same forms, whether in sumproduction of vermilion from mercury and sul mer or in winter : hence we expire more carbon phur is as much an enigma as the formation of in cold weather, and when the barometer is an eye from the substance of the blood.'—p. 12. high, than we do in warm weather; and we
must consume more or less carbon in our food in There are two essential conditions of the same proportion: in Sweden more than in animal life. First, the assimilation or ap- Sicily; and in our more temperate climate a propriation of nourishment; secondly, the full eighth more in winter than in summer. continual absorption of oxygen from the
Even when we consume equal weights of food
in cold and warm countries, infinite wisdom has atmosphere. Now the quantity both of
so arranged, that the articles of food in different food and of oxygen introduced into the climates are most unequal in the proportion of system of an adult is very considerable, carbon they contain. The fruits on which the and yet the weight of his body does not natives of the south prefer to feed do not in the increase: it is clear, therefore, that as much fresh state contain more than per cent. of must be given out as is taken in. But in carbon, while the bacon and train oil used by what form is the oxygen, for example, given from 66 to 80 per cent. of carbon. It is no dif
the inhabitants of the Arctic regions contain out ? It is invariably in combination with ficult matter, in warm climates, to study modecarbon or hydrogen, or both, as water and 'ration in eating, and men can bear hunger for a long time under the equator; but cold and | lers have related with astonishment of these hunger united very soon exhaust the body. people. We should then, also, be able to take
• The mutual action between the elements of ihe same quantity of brandy or train oil without the food and the oxygen conveyed by the circu- bad effects, because the carbon and hydrogen of lation of the blood to every part of the body is these substances would only suffice to keep up THE SOURCE OF ANIMAL HEAT.'--p. 17.
the equilibrium between the external tempera
ture and that of our bodies. We are tempted to continue our extracts • The Englishman in Jamaica sees with refrom this part of the work. Speaking of gret the disappearance of his appetite, previously the uniform temperature of the animal a source of frequently recurring enjoyment; and body, and of the effects of cooling, he says : the most powerful stimulants, in enabling him
he succeeds, by the use of Cayenne pepper and
self to swallow as much food as he was accus"The most trustworthy observations prove tomed to take at home. But the whole of the that in all climates, in the temperate zones as
carbon thus introduced into the system is not well as at the equator or the poles, the tempera- consumed: the temperature of the air is too ture of the body in man, and in what are com- high, and the oppressive heat does not allow monly called warm-blooded animals, is invaria-him to increase the number of respirations by bly the same ; yet how different are the circum- active exercise, and thus to proportion the waste stances under which they live?
to the amount of food taken. Disease of some The animal body is a heated mass, which kind therefore ensues. bears the same relation to surrounding objects
* On the other hand, England sends her sick, as any other heated mass. It receives heat whose diseased digestive organs have in a greatwhen the surrounding objects are hotter, it loses er or less degree lost the power of bringing the heat when they are colder, than itself. We know food into that state in which it is best that the rapidity of cooling increases with the difference between the temperature of the heat- less resistance to the oxidising agency of the
adapted for oxidation-and therefore furnish ed body and that of the surrounding medium; atmosphere than is required in their native that is, the colder the surrounding medium the climate-to southern regions, where the amount shorter the time required for the cooling of the of inspired oxygen is diminished in so great a heated body. How unequal, then, must be the loss of heat in a man at Palermo, where the ex- the health, is obvious. The diseased organs of
proportion: and the result, an improvement in ternal temperature is nearly equal to that of the body, and in the polar regions, where the exter- minished amount of food in equilibrium with the
digestion have sufficient power to place the dinal temperature is from 70° to 90° lower. Yet, inspired oxygen : in the colder climate, the orheat, experience has shown that the blood of gans of respiration themselves would have been the inhabitant of the Arctic circle has a temper- to the action of the atmospheric oxygen.
consumed in furnishing the necessary resistance ature as high as that of the native of the south, who lives in so different a medium. This fact, arising from excess of carbon, prevail in sum
'In our climate, hepatic diseases, or those when its true significance is perceived, proves mer: in winter, pulmonic diseases, or those that the heat given off to the surrounding me
arising from excess of oxygen, are more fredium is restored within the body with great ra
quent. pidity. This compensation takes place more
The cooling of the body, by whatever cause rapidly in winter than in summer, at the pole it may be produced, increases the amount of than at the equator, • In the animal body the food is the fuel ; lair, in a carriage or on the deck of a ship, by
food necessary. The mere exposure to the open with a proper supply of oxygen we obtain the heat given out during its oxidation or combus- the loss of heat, and compels us to eat more
increasing radiation and vaporization, increases tion. In winter, when we take exercise in a
than usual. The same is true of those who are cold atmosphere, and when, consequently, the
accustomed to drink large quantities of cold amount of inspired oxygen increases, the necessity for food containing carbon and hydrogen the body, 98.50.
water, which is given off at the temperature of
It increases the appetite, increases in the same ratio; and by gratifying and persons of weak constitution find it necessathe appetite thus excited, we obtain the most ry, by continued excrcise, to supply to the sysefficient protection against the most piercing tem ihe oxygen required to restore the heat abcold. A starving man is soon frozen to death ; stracted by the cold water. Loud and long-conand every one knows that the animals of prey tinued speaking, the crying of infants, moist air, in the Arctic regions far exceed in voracity those all exert a decided and appreciable influence on of the torrid zone. Our clothing is merely an the amount of food which is taken.'—pp. 23, equivalent for a certain amount of food. "The
24. more warmly we are clothed the less urgent becomes the appetite for food, because the loss of When we read, as we lately did, of five heat by cooling, and consequently the amount substantial meals a day in Calcutta as very of heai to be supplied by food, is diminished. If common, while four are universal there, we were to go naked, like certain savage tribes, can we be surprised at the prevalence of or if in hunting and fishing we were exposed to liver complaint ? or can we doubt that a should be able with ease to consume 10 lbs. of much nearer approach to the native diet flesh, and perhaps a dozen of tallow candles would insure to our countrymen in India a into the bargain, daily, as warmly-clad travel- I condition of health much nearer what they enjoyed at home? The attempt to trans- • In all chronic diseases death is produced by port an English appetite to a tropical cli- the same cause, namely, the chemical action of mate is utterly hopeless, and has cost the atmosphere. When those substances are thousands of valuable lives. Let us hope wanting, whose function in the organism is to that our author's lucid explanation of the eased organs are incapable of performing their
process of respiration; when the discause of liver disease may have some effect proper function of producing these substances: in reforming our habits both in the East when they have lost the power of transforming and West Indies.
the food into that shape in which it may, by enThe accuracy of Professor Liebig's tering into combination with the oxygen of the views of the action of oxygen on the sys- the substance of the organs themselves, the fat tem is shown by the phenomena of starva- of the body, the substance of the muscles, the tion, where the body so rapidly wastes
nerves, and the brain, are unavoidably consumed. a way.
The true cause of death in these cases is the • In the case of a starving man, 32, oz. of respiratory process, that is, the action of the atoxygen enter the system daily, and are given mosphere. Respiration is the falling weight, the out again in combination with a part of his body. bent spring, which keeps the waich in motion: Currie mentions the case of an individual who the inspirations and expirations are the stroke was unable to swallow and whose body lost of the pendulum which regulate it. In our or100lbs. in weight during a month; and, accord- dinary time-pieces, we know with mathematical ing to Martell, a fai pig, overwhelmed in a slip accuracy the effect produced on their rate of of earth, lived 160 days without food, and was going, by changes in the length of the pendulum, found to have diminished in weight, in that time, or in the external temperature. Few, however, more than 120 lbs. The whole history of hyber- | have a clear conception of the influence of air nating animals, and the well-establishled facts and temperature on the health of the human of the periodical accumulation, in various ani- body; and yet the research into the conditions mals, of fat, which, at other periods, entirely necessary to keep it in the normal state is not disappears, prove that the oxygen, in the res
more difficult than in the cas eof a watch.'—p. 29. piratory process, consumes, without exception, all sach substances as are capable of entering trines which would attribute animal heat
After effectually disposing of the docinto combination with it. It combines with whatever is presented to it; and the deficiency of to some mysterious power in the nerves, hydrogen is the only reason why carbonic acid or to the mechanical contraction of the is the chief product: for, at the temperature of muscles, the author proceeds to show that the body, the affinity of hydrogen for oxygen far the quantity of carbon daily converted into surpasses that of carbon for the same element. carbonic acid in an adult, which is 13:9 oz.,
In the progress of starvation, however, it is gives out, in combining with oxygen in not only the fat which disappears, but also, by the body, just as much heat as if burned in degrees, all such of the solids as are capable of being dissolved. In the wasted bodies of those
furnace, and more than enough to account who have suffered starvation, the muscles are for the heat of the body being kept up, for shrunk and unnaturally soft, and have lost their the evaporation of moisture, and for the contractility: all those parts of the body which heat lost by external cooling. The only were capable of entering into the state of motion difference is, that the combustion is very have served to protect the remaiuder of the slow, and the heat is extended over a much frame from the destructive influence of the ai. mosphere. Towards the end, the particles of longer period. Its amount is the same; the brain begin to undergo the process of oxid- its intensity is smaller. He comes to the ation, and delirium, mania, and death close the conclusion that there is nothing yet known scene; that is to say, all resistance to the oxid- to justify the opinion that there exists in ising power of the atmospheric oxygen ceases, the body any other unknown source of and the chemical process of eremacausis, or heat besides ihe chemical action between decay, commences, in which every part of the the oxygen of the air and the elements of body, the bones excepted, enters into combin- | the food. The existence of this cause ation with oxygen.
• The time which is required to cause death by cannot be denied or doubted, and it is starvation depends on the amount of fat in the amply sufficient to explain all the phebody, on the degree of exercise, as in labour or womena. exertion of any kind, on the temperature of the When we turn to the important subject air, and, finally, on the presence or absence of of growth or nutrition, the first point that water. Through the skin and lungs there es- arrests attention is the function of the capes a certain quantity of water, and as the blood, that wonderful fluid out of which all presence of water is essential to the continuance of the vital motions, its dissipation hastens death. the tissues of the body are formed. Cases have occurred in which, a full supply of * All the parts of the animal body are produwater being accessible to the sufferer, death has ced from a peculiar fluid, circulating in its ornot occurred till after the lapse of twenty days. ganism, by virtue of an influence residing in In one case life was sustained in this way for every cell, in every organ, or part of an organ. the period of sixty days.
Physiology teaches that all parts of the body VOL. LXX.
pp. 8, 9.
were originally blood ; or that at least they were | M. Dénis, who has actually succeeded in brought to the growing organs by means of this giving to muscular fibre, by very simple fluid.
* The most ordinary experience further shows, means, all the characters of albumen, out that at each moment of life, in the animal or
of the body. On the other hand, Mulder ganism, a continued change of matter, more or has proved that fibrine and albumen may less accelerated, is going on ; that a part of the be viewed as compounds of a peculiar substructure is transformed into unorganised matter, stance, proteine* (which contains only the Joses its condition of life, and must be again four organic elements). with minute quanrenewed. Physiology has sufficiently decisive tities of sulphur, phosphorus, and salts. grounds for the opinion, that every motion, This explains at once the ready conversion every manifestation of force, is the result of a transformation of the structure or of its sub- of muscle into blood, in the process of distance; that every conception, every mental gestion, and the reconversion of blood into affection, is followed by changes in the chemical muscle, in that of growth. Albumen is nature of the secreted fluids ; that every thought, converted into blood or muscle with the every sensation, is accompanied by a change in same facility; and all these transformations the composition of the substance of the brain. in animals, certain matters are required, parts tion of proteine is the same In order to keep up the phenomena of life occur without the addition or the removal
of any organic element: for the composiof organisms, which we call nourishment. In
as that of consequence of a series of alterations, they serve fibrine and albumen, excluding the mineeither for the increase of the mass (nutrition), ral ingredients, which form a small fraction or for the supply of the matter consumed (repro- of the two latter. duction), or, finally, for the production of force.'- The author proceeds to show that this
very remarkable identity in composition Now, the blood contains two principal enables us to understand very easily the constituents : fibrine, which forms the ciot, process of nutrition in the carnivora : for and albumen, which is dissolved in the their food consists of muscle, of albuminous serum : the former is identical with pure tissues, of blood-in short, of compounds muscular fibre, the latter with white of of proteine. These animals may be said eggs. Here chemistry steps in, and shows to devour themselves, for their food has that, as far as regards their organic ele- the same composition as their bodies. By ments (carbon, nitrogen, hydrogen, and the very recent researches of Mulder, oxygen), these iwo bodies are identical in Scherer, and Bence Jones, it has been composition; and that they differ only in shown that all the tissues of the body, the the proportions, absolutely very small, of composition of which differs from that of sulphur, phosphorus, and saline matters fibrine or albumen, are yet closely related which they contain.
10 proteine. Thus we may express the This important and unexpected fact, composition of the chief animal solids as first observed by Mulder, has been very follows (P represents phosphorus, S sulrecently established beyond all doubt by phur) : Albumen
is proteine + P + St + salts. Fibrine .
is proteine + P + 2 S + salts. Caseine
is proteine + S + salts. Arterial membrane is proteine + water. Chondrine
is proteine + water + oxygen. Hair, horn, &c. are proteine + ammonia + oxygen.
Gelatinous tissue . is proteine + ammonia + water + oxygen. Now it is obvious, that if proteine be product of the decomposition of animal present in the food, the other necessary matter. elements are all ready at hand. For ani- Let us now consider the nutrition of mal food, of course, contains as much phos- herbivorous animals. Whence do they obphorus, sulphur, and salts as the body to tain the means of producing their blood ? be nourished; while oxygen and water are It is here that chemistry again comes to always present, and ammonia is a constant our aid, and points to the remarkable fact,
that all vegetable matters capable of sup
porting animal life contain more or less * Mulder, having discovered that fibrine, albumen, and almost all the animal tissues, when acted all the others were derived, the name of proteine on by potash, which dissolves them, and the solu-|(from xpwrevw, I take the first place). tions precipitated by acetic acid, yield a peculiar + P. and S. do not stand for equivalents, but for compound, the same in every case, and the organic certain very small quantities, much under ! per composition of which was the same as that ofcent., of phosphorus and sulphur. In the remaining fibrine and albumen, while it contained no inor-compounds, the water, oxygen, and ammonia are ganic matter, gave to this compound, which he con- | merely expressed generally, without reference here to sidered as the original organic product, from which their actual quantity.
nitrogen ; an element indispensable to the afterwards separated, exactly as fibrine does existence of blood, as well as of every or
from blood. ganised animal solid. But in what form
• The second nitrogenised compound remains does nitrogen exist in these nutritious fibrine. It does not separate from the juice at
dissolved in the juice after the separation of the vegetables
the ordinary temperature, but is instantly coagThere are found in the vegetable king-ulated
when the liquid
containing it is heated to dom three nitrogenised compounds, which the boiling point. When the clarified juice of alone are capable of supporting animal life, nutritious vegetables
, such as cauliflower, and these have been called vegetable asparagus, mangel-wurzel, or turnips, is made fibrine, albumen, and caseine. The truly to boil,
a coagulum is formed, which it is absointeresting result of recent investigations stance which separates as a coagulum, when the is, that these three compounds are, in serum of blood or the white of an egg, diluted composition and chemical properties, ab- with water, are heated to the boiling-point
. solutely identical with the corresponding This is vegetable albumen. It is found in the animal principles. All are compounds of greatest abundance in certain seeds, in puts, alproteine; and while the whole six are monds, and others, in which the starch of the identical in the proportion of organic ele- gramineæ is replaced by oil.
•The third nitrogenised constituent of the vements, vegetable albumen is found to contain the same mineral elements as animal is chiefly found in the seeds of peas, beans, len
getable food of animals is vegetable caseine. It albumen, vegetable fibrine as animal tils, and similar leguminous seeds. Like vege-, fibrine, and vegetable caseine as animal table albumen, it is soluble in water, but differs caseine (milk, cheese).
from it in this, that its solution is not coagulated by heat. When the solution is heated or eva
porated, a skin forms on its surface, and the ad * All such parts of vegetables as can afford nu- dition of an acid causes a coagulum, just as in triment to animals contain certain constituents animal milk. which are rich in nitrogen; and the most or- These three compounds are the true nitrodinary experience proves that animals require genised constituents of the food of graminivorous for their support and nutrition less of these parts animals; all other nitrogenised compounds ocof plants in proportion as they abound in the curring in plants are either rejected by animals, nitrogenised constituents. Animals cannot be as in the case of the characteristic principles of sed on matters destitute of these nitrogenised poisonous and medicinal plants, or else they occonstituents. These important products of ve- cur in the food in such very small proportion, getation are especially abundant in the seeds of that they cannot possibly contribute to the inthe different kinds of grain, and of peas, beans, crease of mass in the animal body. and lentils; in the roots and the juices of what • The chemical analysis of these three subare commonly called vegetables. They exist, stances has led to the very interesting result that however, in all plants, without exception, and they contain the same organic elements, united in every part of plants in larger or smaller quan- in the same proportion by weight; and, what is tily. These nitrogenised forms of nutriment in still more remarkable, that they are identical in the vegetable kingdom may be reduced to three composition with the chief constituents of blood, substances, which are easily distinguished by animal fibrine and albumen. They all three their external characters. Two of them are dissolve in concentrated muriatic acid with the soluble in water, the third is insoluble. same deep purple colour; and even in their
• When the newly-expressed juices of vegeta- physical characters, animal fibrine and albumen bles are allowed to stand, a separation takes are in no respect different from vegetable fibrine place in a few minutes. A gelatinous precipi- and albumen. It is especially to be noticed, tate, commonly of a green tinge, is deposited, that by the phrase-identity of composition and this, when acted on by liquids which re- we do not here imply mere similarity, but that move the colouring matter, leaves a greyish even in regard to the presence and relative white substance, well known to druggists as the amount of sulphur, phosphorus, and phosphate deposit from vegetable juices. This is one of of lime, no difference can be observed. the nitrogenised compounds which serves for the • How beautifully and admirably simple, with nutrition of animals, and has been named vege- the aid of these discoveries, appears the process table fibrine. The juice of grapes is especially of nutrition in animals, the formation of their rich in this constituent, but it is most abundant organs, in which vitality chiefly resides! Those in the seeds of wheat, and of the cerealia ge- vegetable principles, which in animals are used nerally. It may be obtained from wheat flour to form blood, contain the chief constituents of by a mechanical operation, and in a state of blood, fibrine and albumen, ready forined, as far tolerable purity : it is then called gluten, but as regards their composition. All plants, be the glutinous property belongs not to vegetable sides, contain a certain quantity of iron, which fibrine, but to a foreign substance, present in re-appears in the colouring-matter of the blood. small quantity, which is not found in the other Vegetable fibrine and animal fibrine, vegetable cerealia. The method by which it is obtained albumen and animal albumen, hardly differ, sufficiently proves that it is insoluble in water; even in form : if these principles be wanting in although we cannot doubt that it was originally the food, the nutrition of the animal is arrested; dissolved in the vegetable juice, from which it and when they are present, the graminivorous